1. Technical Field
This invention generally relates to a sport's instructional aid and in particular it relates to an instructional aid, used on the tennis court, for teaching the proper positioning of a tennis player relative to the bounce of the tennis ball.
2. Background Art.
Most athletic endeavors, whether team sports or individual sports, involve being at the right place at the right time. Tennis is no exception. A tennis player must judge the bounce of the tennis ball relative to its origin and adjust his position accordingly so that he can return the stroked ball.
Assuming that the most desireable stroke in returning a tennis ball is a level, waist high, stroke, the player must position himself relative to the bounce of the tennis ball such that the tennis ball will be at the right height for the return stroke.
ENGLE, U.S. Pat. No. 2,458,984 teaches a football instructing device. The device is intended for use by running backs practicing pre-planned movement as required by particular plays. The device essentially takes the place of other players by indicating their relative positions on the playing field.
A particular tennis instructional aid is taught by DOMBROWSKI, ET AL., U.S. Pat. No. 4,711,633. Dombrowski teaches a layered wheel calculator for identifying stroke and grip problems. The tennis player uses the calculator to correlate potential problem sources with the undesirable result they are experiencing. It does not teach positioning.
In tennis, the return of a ball that has bounced on the player's side of the court is called a ground stroke. The optimum distance behind the bounce point of a tennis ball, which corresponds to the longitudinal range in which the tennis ball is at waist height in its trajectory, is dependent upon three factors. Neglecting air resistance, the factors are: initial velocity, angle of trajectory and spin. Obviously, there is a great deal of interrelation between the three factors. A tennis ball ground stroked from deep in the opposing player's court will require a high velocity and a corresponding smaller angle of trajectory to clear the net and at the same time stay in bounds. If the player were to use a top spin shot in hitting the deep ground stroke, he could increase both the initial velocity and angle of trajectory while still keeping the ball in play. Obviously, novice players cannot afford to be overly concerned with trying to analyze the opposing player's distance away from the net, initial velocity, trajectory angle and the spin on the tennis ball. Most novice players are simply trying to get the ball over the net while keeping it in bounds.
What is needed is an instructional aid which demonstrates to the tennis player the proper positioning behind the bounce point of a ground stroked tennis ball for the return stroke.
It is therefore an object of the present invention to provide a tennis instructional aid which a novice player, or any player wishing to improve his or her game, can use to insure optimum positioning behind the bounce point of a ground stroked tennis ball.